• 
• 

Three Part Question

In [a haemodynamically unstable patient with atrial fibrillation undergoing electrical cardioversion] does [sedation or rapid sequence induction] lead to [lower mortality, less respiratory complications, and shorter length of hospital stay]?

Clinical Scenario

A 45 year old man is brought to Accident and Emergency by ambulance. On arrival his systolic blood pressure is 88mmHg, his GCS is reduced and an ECG reveals atrial fibrillation with a ventricular rate of 141bpm. You decide he needs cardioverting immediately to restore sinus rhythm but wonder whether sedation or rapid sequence induction is safer.

Search Strategy

Medline 1950 to June Week 3 2008
Embase 1980 to 2008 Week 26
Cochrane Central Register of Controlled Trials 2nd Quarter 2008

[exp atrial fibrillation/ or atrial fibrillation.mp.] AND [exp intubation/ or intubation.mp. or intubate$.mp. or exp etomidate/ or amidate.mp. or exp propofol/ or diprivan.mp. or rapid sequence induction.mp. or rsi.mp. or crash induction.mp. or airway management.mp.] AND [exp "Hypnotics and Sedatives"/ or sedation.mp. or sedat$.mp. or hypnotic$.mp. or exp midazolam/ or midazolam.mp. or exp diazepam/ or diazepam.mp. or exp lorazepam/ or lorazepam.mp. or exp benzodiazepines/ or benzodiazepine$.mp. or exp propofol/ or "propofol".mp.] AND [exp electric countershock/ or electrical cardioversion.mp. or DC cardioversion.mp. or exp anti arrhythmia agents/ or chemical cardioversion.mp. or DC shock.mp] LIMIT to humans AND English language

Search Outcome

84 papers found of which none were directly relevant to the clinical question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses

Comment(s)

There were no articles comparing the use of anaesthetic agent with sedative for the emergency cardioversion of unstable AF. Parlak et al. carried out a randomized blinded clinical trial comparing midazolam (2mg IV over 30s, then 1mg every 2min) vs propofol (20mg IV over 30s then 20mg every 2min) in 2 diffferent age-groups (<65 and >65) with respect to induction time (time to reach RSS5), recovery time (RSS2) and side effects including desaturations, apneas, changes of haemodynamic parameters and patient reactions. They found that induction time was similar in all 4 groups, recovery time was shorter in both propofol groups (p=0.001) and more patients in the elder midazolam group experienced desaturations and apneas than in the elder propofol group, whilst there was no significant differences in side effects between the younger age groups. They concluded that propofol was superior to midazolam for CV sedation, especially in older individuals. DW Gale et al. carried out a prospective, randomized, single-blind comparative study comparing propofol, midazolam, and methohexital as titrated infusions for sedation of elective electrical cardioversion. They found that all three drugs were acceptable choices but that propofol and methohexital were superior to midazolam in their ability to provide rapid anaesthetic onset and recovery. The time to awakening in the midazolam group was 33±11 mins, compared to 11±4 mins and 9±3 mins in propofol and methohexital groups respectively. (p<0.0001). A similar result was seen with time to induction (midazolam 2.7±1.1 mins, propofol 1.6±0.3 mins and methohexital 1.7±0.4 mins). This result is conflicting to that of the study be Parlak et al. which found induction times between propofol and midazolam to be similar. The reason for this difference may be because in the present study all drugs were administered as fixed infusions based on predetermined concentration rather than on a mg/kg/min basis, thus these numbers may not reflect a true comparison of induction times. With regards to safety, propofol did tend to have a greater decrease in mean arterial pressure after induction than either methohexital or midazolam. But this variance was not significant when compared within specified time intervals. Also, it caused significantly more pain on injection than either of the other two agents. R Canessa prospectively compared etomidate (0.15mg/kg IV over 30s), thiopental (3mg/kg IV over 30s), propofol (1.5mg/kg IV over 30s) and midazolam (0.15mg/kg IV over 30s) for sedation in elective cardioversion of atrial fibrillation with regards to induction time, awakening time and the incidence of adverse effects. They found that all four drugs provided satisfactory anaesthesia for cardioversion with midazolam taking a significantly longer time for induction and recovery than the other three, whilst also having more pronounced interindividual variability. This is in keeping with results from the study by Gale et al. With respect to systolic arterial pressure, significant decreases were seen with midazolam and thiopental, and even more so with propofol. Though with thiopental and midazolam, blood pressure returned to baseline after cardioversion whereas with propofol it remained below baseline. There were no significant changes in the blood pressure of patients receiving etomidate. Significantly more apneas occurred in the propofol group than the others. BG Goldner et al. compared sedation with propofol (1 mg/kg) by an anaesthesiologist to sedation with midazolam (1mg IV) and morphine by an electrophysiologist, for elective cardioversion of patients with atrial fibrillation. They found that time to sedation (no response to soft verbal and mild tactile stimuli) was significantly shorter using propofol (3±2 mins) than for midazolam (9±4 mins) (p=0.0001). Time to return of consciousness was not significantly different. Due to the lack of evidence investigating the safety and efficacy of sedatives for use in emergent cardioversion of unstable atrial fibrillation, it is not possible to establish a definite recommendation. However, there is evidence from several studies to show that both thiopental and propofol significantly lower blood pressure in elective cardioversion. There is conflicting evidence from different sources on the time for induction and recovery of sedation for midazolam, this may be due to different study protocols. Overall it appears that midazolam has a longer time to induction and recovery than propofol.

Clinical Bottom Line

There is no available evidence to guide the decision to sedate or intubate prior to emergency cardioversion in haemodynamically unstable patients with atrial fibrillation. A careful appraisal of the risks and benefits of each approach by skilled personnel is warranted on a case by case basis.

References

1. Gale DW, Grissom TE, Mirenda JV Titration of intravenous anesthetics for cardioversion: a comparison of propofol, methohexital, and midazolam Critical Care Medicine. 1993; 21(10):1509-13.
2. Parlak M., Parlak I., Erdur B., Ergin A., Sagiroglu E. Age Effect on Efficacy and Side Effects of Two Sedation and Analgesia Protocols on Patients Going through Cardioversion: A Randomized Clinical Trial Academic Emergency Medicine 2006; 13(5): 493-499
3. Canessa R. Lema G. Urzua J. Dagnino J. Concha M. Anesthesia for elective cardioversion: a comparison of four anesthetic agents Journal of Cardiothoracic & Vascular Anesthesia 1991; 5(6):566-8
4. Goldner BG. Baker J. Accordino A. Sabatino L. DiGiulio M. Kalenderian D. Lin D. Zambrotta V. Stechel J. Maccaro P. Jadonath R. Electrical cardioversion of atrial fibrillation or flutter with conscious sedation in the age of cost containment American Heart Journal 1998; 136(6):961-4